The electric field is thus seen to depend only on the charge
$Q$ and the distance
$r$ ; it is completely independent of the test charge
$q$ .
Calculating the electric field of a point charge
Calculate the strength and direction of the electric field
$E$ due to a point charge of 2.00 nC (nano-Coulombs) at a distance of 5.00 mm from the charge.
Strategy
We can find the electric field created by a point charge by using the equation
$E=\text{kQ}/{r}^{2}$ .
Solution
Here
$Q=2\text{.}\text{00}\times {\text{10}}^{-9}$ C and
$r=5\text{.}\text{00}\times {\text{10}}^{-3}$ m. Entering those values into the above equation gives
This
electric field strength is the same at any point 5.00 mm away from the charge
$Q$ that creates the field. It is positive, meaning that it has a direction pointing away from the charge
$Q$ .
Calculating the force exerted on a point charge by an electric field
What force does the electric field found in the previous example exert on a point charge of
$\mathrm{\u20130.250}\phantom{\rule{0.25em}{0ex}}\mu \text{C}$ ?
Strategy
Since we know the electric field strength and the charge in the field, the force on that charge can be calculated using the definition of electric field
$\mathbf{\text{E}}=\mathbf{\text{F}}/q$ rearranged to
$\mathbf{\text{F}}=q\mathbf{\text{E}}$ .
Solution
The magnitude of the force on a charge
$q=-0\text{.}\text{250}\phantom{\rule{0.25em}{0ex}}\text{\mu C}$ exerted by a field of strength
$E=7\text{.}\text{20}\times {\text{10}}^{5}$ N/C is thus,
Because
$q$ is negative, the force is directed opposite to the direction of the field.
Discussion
The force is attractive, as expected for unlike charges. (The field was created by a positive charge and here acts on a negative charge.) The charges in this example are typical of common static electricity, and the modest attractive force obtained is similar to forces experienced in static cling and similar situations.
Play ball! Add charges to the Field of Dreams and see how they react to the electric field. Turn on a background electric field and adjust the direction and magnitude.
Section summary
The electrostatic force field surrounding a charged object extends out into space in all directions.
The electrostatic force exerted by a point charge on a test charge at a distance
$r$ depends on the charge of both charges, as well as the distance between the two.
The electric field
$\mathbf{\text{E}}$ is defined to be
$\mathbf{\text{E}}=\frac{\mathbf{\text{F}}}{q,}$
where
$\mathbf{\text{F}}$ is the Coulomb or electrostatic force exerted on a small positive test charge
$q$ .
$\mathbf{\text{E}}$ has units of N/C.
The magnitude of the electric field
$\mathbf{\text{E}}$ created by a point charge
$Q$ is
What is the magnitude and direction of an electric field that exerts a
$2\text{.}\text{00}\times {\text{10}}^{-5}\phantom{\rule{0.25em}{0ex}}\text{N}$ upward force on a
$\mathrm{\u20131.75}\phantom{\rule{0.25em}{0ex}}\mu \text{C}$ charge?
What is the magnitude and direction of the force exerted on a
$3.50\phantom{\rule{0.25em}{0ex}}\mu \text{C}$ charge by a 250 N/C electric field that points due east?
Calculate the initial (from rest) acceleration of a proton in a
$5\text{.}\text{00}\times {\text{10}}^{6}\phantom{\rule{0.25em}{0ex}}\text{N/C}$ electric field (such as created by a research Van de Graaff). Explicitly show how you follow the steps in the Problem-Solving Strategy for electrostatics.
(a) Find the direction and magnitude of an electric field that exerts a
$4\text{.}\text{80}\times {\text{10}}^{-\text{17}}\phantom{\rule{0.25em}{0ex}}\text{N}$ westward force on an electron. (b) What magnitude and direction force does this field exert on a proton?
An American traveler in New Zealand carries a transformer to convert New Zealand’s standard 240 V to 120 V so that she can use some small appliances on her trip.
The potential difference between any two points on the surface is zero that implies È.Ŕ=0, Where R is the distance between two different points &E= Electric field intensity. From which we have cos þ =0, where þ is the angle between the directions of field and distance line, as E andR are zero. Thus
MAHADEV
sorry..E and R are non zero...
MAHADEV
By how much leeway (both percentage and mass) would you have in the selection of the mass of the object in the previous problem if you did not wish the new period to be greater than 2.01 s or less than 1.99 s?
Physics is the branch of science that deals with the study of matter and the interactions it undergoes with energy
Junior
it is branch of science which deals with study of happening in the human life
AMIT
A 20MH coil has a resistance of 50 ohms and is connected in series with a capacitor to a 250MV supply
if the circuit is to resonate at 100KHZ,
Determine
1: the capacitance of the capacitor
2: the working voltage of the circuit,
given that pie =3.142
Musa
Physics is the branch of science that deals with the study of matter and the interactions it undergoes with energy
Kelly
Heat is transfered by thermal contact but if it is transfered by conduction or radiation, is it possible to reach in thermal equilibrium?
Physics? Is a branch of science dealing with matter in relation to energy.
Moses
Physic... Is a purging medicine, which stimulates evacuation of the bowels.
Moses
are you asking for qualities or quantities?
Noman
fundamental quantities are,
length ,
mass,
time,
current,
luminous intensity,
amount of substance,
thermodynamic temperature.
Shravasti
fundamental quantities are quantities that are independent of others and cannot be define in terms of other quantities
there is nothing like Qualities we have only fundamental quantities which includes; length,mass,time, electric current, luminous density, temperature, amount of substance etc
Gift
give examples of three dimensional frame of reference
Examine different types of shoes, including sports shoes and thongs. In terms of physics, why are the bottom surfaces designed as they are? What differences will dry and wet conditions make for these surfaces?
sports shoes are designed in such a way they are gripped well with your feet and their bases have and high friction surfaces,
Thong shoes are for comfort, these are easily removed and light weight.
these are usually low friction surfaces but in wet conditions they offer greater friction.